Field
The embodiments of this disclosure are directed to an electrostatic capacity type touch screen panel.
Related Art
Display apparatuses, such as liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panel (PDP) displays, and electroluminescent (EL) displays, attract attention due to high response speed, low power consumption, and high color reproduction ratio. Such display apparatuses are used for various electronics including TVs, computer monitors, laptop computers, mobile phones, displays for refrigerators, personal digital assistants, automated teller machines. In general, these display apparatuses constitute an interface with users using various input devices, such as a keyboard, mouse, digitizers, or more. However, the keyboard or mouse is disadvantageous in that a user needs to learn how to use and it occupies a space. In response to increased demand for simple and less malfunctioned input devices, touch screen panels have been suggested that allow a user to directly input information with his/her hand or pen.
Because the touch screen panel has a simple configuration, which minimizes erroneous operations, the user can perform an input action without using a separate input device, and can quickly and easily manipulate through contents displayed on a screen. Accordingly, the touch screen panel has been applied to various display devices.
Touch screen panels are classified into a resistive type, an electrostatic capacitive type, an electromagnetic type according to a detection method of a touched portion. The resistive type touch screen panel determines a touched position by a voltage gradient according to a change of resistance in a state that a DC voltage is applied to metal electrodes formed on an upper plate or a lower plate. The electrostatic capacitive type touch screen panel senses a touched position according to a difference in capacitance created in an upper or lower plate when the user physically contacts with a conductive film formed on the upper or lower plate. The electromagnetic type touch screen panel detects a touched portion by reading an LC value induced as an electromagnetic pen touches a conductive film.
Hereinafter, a related art electrostatic capacitive type touch screen panel will be described with reference to FIGS. 1 to 2B. FIG. 1 is a top plan view illustrating a related art electrostatic capacitive type touch screen panel, FIG. 2A is a cross-sectional view illustrating the touch screen panel taken along line I-I′ of FIG. 1, and FIG. 2B is a cross-sectional view illustrating the touch screen panel taken along line II-II′ of FIG. 1.
Referring to FIGS. 1, 2A and 2B, the related art electrostatic capacitive type touch screen panel includes an electrode forming part A, a routing wire forming part B, a pad forming part C formed on a substrate 10.
The electrode forming part A is formed on a substrate 10 and includes a plurality of first electrode patterns 40 arranged in parallel in a first direction (for example, X-axis direction), a plurality of bridges 20 connecting the neighboring first electrode patterns 40 each other, and a plurality of second electrode patterns 50 arranged in a second direction (for example, Y-axis direction) to cross over the first electrode patterns 40.
The routing wire forming part B is formed on the substrate 10 at positions outside the electrode forming part A and includes a plurality of first routing wires 61 connected to the plurality of first electrode patterns 40, respectively, and a plurality of second routing wires 63 connected to the plurality of second electrode patterns 50, respectively.
The pad forming part C includes a plurality of first pads 71 connected to the plurality of first electrode patterns 40 through the plurality of first routing wires 61, respectively, and a plurality of second pads 73 connected to the plurality of second electrodes 50 through the plurality of second routing wires 63, respectively.
The electrostatic capacitive type touch screen panel also includes an insulation layer 30. The insulation layer 30 is formed on the substrate 10 on which the bridges 20 and the first and second routing wires 61 and 63 are formed, and electrically insulate the first electrode patterns 40 from the second electrode patterns 50. The insulation layer 30 includes first contact holes 33 exposing the bridges 20 and second contact holes 35 exposing the first and second routing wires 61 and 63.
In order to assemble the related art touch screen panel to a display panel, it is necessary for a module process to attach a polarizing sheet, a print circuit board, a backlight unit and so on to the display panel. In the first step of the module process, an abrasive belt for removing a pollution material on the display panel is used. However there are scratches on surface of electrode patterns of the touch screen panel by the abrasive belt.
FIG. 3A is a conceptual view schematically illustrating a module-cleaning process of the display panel having the touch screen panel, and FIG. 3B is a SEM (Scanning Electron Microscope) photograph taking a picture of “R” portion of FIG. 3A.
Referring FIG. 3A, for the module-cleaning process, the display panel DP having the touch screen panel TSP is moved along an arrow direction “a” by the carrier roller T. Abrasive belts AB are disposed on an upper side of the touch screen panel TSP and on a lower side of the display panel DP, respectively. The abrasive belts are rotated along arrow directions “b”. Accordingly, the pollution materials on the surfaces of the touch screen panel TSP and the display panel DP are removed by abrasion between the abrasive belts AB and the surfaces.
However, the second electrode pattern 50 of the touch screen panel TSP has a “R” portion (hereinafter, it is also referred to as “a step coverage”) which is protruded upward because the bridge 20 is formed on the substrate 10 and the bridge 20 is covered with the insulation layer 30 as shown in FIG. 3A. There may be a scratch on the “R” portion of the second electrode pattern 50 when the display panel DP having the touch screen panel TSP is moved along the arrow direction “a” and the abrasive belts AB are rotated along the arrow direction “b” because the “R” portion is protruded upward from other portions.
FIG. 3B is a SEM (Scanning Electron Microscope) photograph taking a picture of “R” portion of FIG. 3A, and shows a state that the second electrode pattern 50 is opened by the scratch of the “R” portion.
If the second electrode pattern 50 of the touch screen panel TSP is opened, it is impossible to perceive a touch operation when the touch screen panel is touched with a finger, a pen and so on.